Companion planting can also be practiced in containers too! You may have to get a larger container based on what you will be planting but many of the vegetables "companion" plants are herbs which don't take up a lot of space. Here is a website dedicated to seeds specifically for containers. Check it out!
Spring is not far off! Get your seeds now! I have heard from more than one source that the prices on produce in the grocery stores will be significantly higher. So get yourself ready....so all of your produce will be virtually free!